go/src/pkg/sync/cond_test.go

// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package sync_test

import (
	. "sync"
	"testing"
)

func TestCondSignal(t *testing.T) {
	var m Mutex
	c := NewCond(&m)
	n := 2
	running := make(chan bool, n)
	awake := make(chan bool, n)
	for i := 0; i < n; i++ {
		go func() {
			m.Lock()
			running <- true
			c.Wait()
			awake <- true
			m.Unlock()
		}()
	}
	for i := 0; i < n; i++ {
		<-running // Wait for everyone to run.
	}
	for n > 0 {
		select {
		case <-awake:
			t.Fatal("goroutine not asleep")
		default:
		}
		m.Lock()
		c.Signal()
		m.Unlock()
		<-awake // Will deadlock if no goroutine wakes up
		select {
		case <-awake:
			t.Fatal("too many goroutines awake")
		default:
		}
		n--
	}
	c.Signal()
}

func TestCondSignalGenerations(t *testing.T) {
	var m Mutex
	c := NewCond(&m)
	n := 100
	running := make(chan bool, n)
	awake := make(chan int, n)
	for i := 0; i < n; i++ {
		go func(i int) {
			m.Lock()
			running <- true
			c.Wait()
			awake <- i
			m.Unlock()
		}(i)
		if i > 0 {
			a := <-awake
			if a != i-1 {
				t.Fatalf("wrong goroutine woke up: want %d, got %d", i-1, a)
			}
		}
		<-running
		m.Lock()
		c.Signal()
		m.Unlock()
	}
}

func TestCondBroadcast(t *testing.T) {
	var m Mutex
	c := NewCond(&m)
	n := 200
	running := make(chan int, n)
	awake := make(chan int, n)
	exit := false
	for i := 0; i < n; i++ {
		go func(g int) {
			m.Lock()
			for !exit {
				running <- g
				c.Wait()
				awake <- g
			}
			m.Unlock()
		}(i)
	}
	for i := 0; i < n; i++ {
		for i := 0; i < n; i++ {
			<-running // Will deadlock unless n are running.
		}
		if i == n-1 {
			m.Lock()
			exit = true
			m.Unlock()
		}
		select {
		case <-awake:
			t.Fatal("goroutine not asleep")
		default:
		}
		m.Lock()
		c.Broadcast()
		m.Unlock()
		seen := make([]bool, n)
		for i := 0; i < n; i++ {
			g := <-awake
			if seen[g] {
				t.Fatal("goroutine woke up twice")
			}
			seen[g] = true
		}
	}
	select {
	case <-running:
		t.Fatal("goroutine did not exit")
	default:
	}
	c.Broadcast()
}